This application relates to an auxiliary oil system to supplement a main oil supply system on a gas turbine engine with a gear drive for a fan.
Gas turbine engines are known and, typically, include a fan delivering air into a bypass duct as propulsion air and also delivering air into a core engine. The core engine flow passes into a compressor where it is compressed and then delivered into a combustion section. The compressed air is mixed with fuel and ignited in the combustion section and products of this combustion pass downstream over turbine rotors driving them to rotate.
Historically, a turbine rotor drove the fan rotor at a single speed. This led to compromise in the desired speed for both the fan rotor and the turbine rotor. The fan rotor could not rotate unduly fast and, thus, the turbine rotor typically rotated slower than would be desired.
More recently, it has been proposed to include a gear reduction between a fan drive turbine and the fan rotor. This has allowed the fan to rotate at slower speeds and results in many efficiencies.
However, the gear reduction requires adequate lubrication and must be lubricated even under extreme flight conditions.